1. Field of the Invention
This invention relates to gas turbine engines, and more particularly to a seal member disposed between the platforms of an array of rotor blades and a rotor disk.
2. Description of the Prior Art
A gas turbine engine has a compression section, a combustion section and a turbine section. A rotor extends axially through the compression section and the turbine section. Each rotor has at least one rotor disk and a plurality of outwardly extending airfoil-shaped rotor blades. A working medium flowpath extends axially between the rotor blades. The rotor blades have platforms which cooperate to provide a boundary to the flowpath. Working medium gases directed along the flowpath through the blades, receive energy from the blades in the compression section and impart energy to the blades in the turbine section.
Because the platforms of the blades are spaced from each other and from the disk sidewalls leaving gaps therebetween, the working medium gases in some constructions leak from the prescribed flowpath at a region of high pressure by flowing through the gaps, under the platforms into the spaces between the platforms and the disk, and thence out into the flowpath at a region of lower pressure. Structures having the sealing effectiveness to block such leakage are required to avoid adverse effects on the performance of the engine.
One example of a structure blocking the leakage of working medium gases between adjacent platforms is shown in U.S. Pat. No. 3,972,645 to Kasprow. Kasprow provides a ladder-type rim seal having circumferentially spaced crossbars interconnected at opposite ends by longitudinally extending strips integral with the crossbars at the end.
Easy assembly of the rim seal and the rotor blades to the rotor disk is known to be desirable and is provided in Kasprow by both a radial clearance and an axial clearance between the seal and the rotor disk. More importantly, effective sealing between adjacent blade platforms is provided by the ladder structure of Kasprow. Still, scientists and engineers continue to seek more effective rim seals while maintaining the facileness with which assembly is performed.